JERRY NADLER, (D) NEW YORK, SAYING: "We've told him we expect him to show up on Thursday and we're going to conduct the inquiry as we said we would.

If he doesn't show up Thursday then we'll have to go to subpoenas." Barr released his redacted version of Mueller's report in mid-April.

The report cleared President Donald Trump of conspiracy with the Russians, but laid out 10 episodes Mueller said showed Trump had tried to impede his investigation, including asking his White House counsel to have Mueller fired.

Mueller stopped short of concluding Trump had committed a crime, noting that Congress has the power to address whether Trump violated the law.

In light of the report, Democrats want to know why Barr himself decided not to pursue obstruction charges against Trump.

The House panel has also asked Mueller to testify.

The dispute comes amid deepening tensions between Democrats and Trump, who has said he will vigorously fight a wave of subpoenas seeking his taxes and financial records, as well as Mueller's full unredacted report.

Barr is also due to testify before the Senate Judiciary Committee on Wednesday.